Carbonaceous adsorbent for removal of pyrogen and method of producing pure water using same

ABSTRACT

A carbonaceous absorbent to be used for the removal of a pyrogen dissolved in water is disclosed. The absorbent is obtained by carbonizing porous beads of a cross-linked polymer. This absorbent is favorably used for the removal of endotoxin in the production of pure water from deionized water resulting from the treatment with iron-exchange resins.

BACKGROUND OF THE INVENTION:

a. Field of the Invention:

This invention relates to a carbonaceous adsorbent to be used for theremoval of a pyrogen dissolved in water. It also relates to a method forthe removal of endotoxin with the carbonaceous adsorbent in theproduction of pure water from deionized water resulting from thetreatment with ion-exchange resins.

b. Description of the Prior Art:

The "pyrogen" is the generic term applied to all substances which, evenin an extremely small amount, cause abnormal elevation of bodytemperatures of homothermal animals. If a pyrogen finds its way into theblood in a human body as by intravenous injection of a medicine, itcauses a violent exothermic reaction independently of the principalaction of the medicine. In an extreme case, this exothermic reactioncould result in fatal shock.

The pyrogenic toxin consists mainly of the bacterial endotoxin which isa compound lipopolysaccharide occurring as the cell membrane componentof gram negative bacteria. The pharmacopoeia in numerous countriesprohibit solutions for injection from containing pyrogens as well asmicroorganisms. The integration of semiconductor elements has advancedto a point where the so-called superpure water obtained by enhancing thepurity of normally pure water ultimately to suit production of suchsemiconductor elements is now required to meet the exacting standardthat the number of live microorganisms, the source of pyrogen, shouldnot exceed 0.02/ml.

Production of pure water containing no pyrogen is generally effected byfollowing the operation of distillation defined by the Pharmacopoeia forthe purification of water. The pure water obtained by just one round ofthe distillation, more often than not, gives a positive result in theLimulus test (the test resorting to the gelling reaction of the limulusamberbocyte lysate with endotoxin).

Heretofore, as means of removing pyrogenic substances, the treatmentusing powdered granulated activated carbon and the treatment using avarying species of ion-exchange resin have been tried. These treatments,however, often experience leaks of liquids under treatment owing tovariation of load of pyrogenic substance and cannot be expected to givea stable effect. Thus, as disclosed in Japanese Patent No. 989,058titled "Method for obtaining refined sugar solution containing nopyrogenic substance" and Japanese Patent No. 738,632 titled "Method forobtaining aqueous solution for injection containing neither pyrogen normicroorganism by treatment of filtration", for example, the membraneseparation method using a filtration membrane has come to findwidespread acceptance.

Generally, the membrane separation method, instead of beingindependently used, is incorporated as one element in the extremelyexpensive system for the production of superpure water. To be specific,this is a method which comprises passing town water containing variousions and organic substances as well as pyrogens in large amounts throughactivated carbon and/or ion-exchange resin, storing the treated water,and forwarding the water for further treatments through an ultravioletlight sterilizer, a regeneration type mixed-bed type ion-exchange resincolumn, and a filtration membrane such as an ultrafiltration membrane ora reverse-osmosis membrane. Microorganisms by nature possess amultiplying property. The microorganisms in the water under treatment,even after sterilization of the water, are captured within the system,particularly on the surface of a filtration membrane. In consequence ofthe growth of the number of killed microorganisms, the concentration ofendotoxin continues to increase possibly to the extent of inducing earlyclogging of the membrane and constituting one factor for the unexpectedimpairment of the membrane quality.

It is known that once the pyrogen-free water obtained as described aboveis released from the germ-free condition, it is highly susceptible tomicro-organic contamination and is liable to suffer quick formation ofendotoxin. In the circumstances, the desirability of developing amedicine, a special adsorbent, or other similar means capable of easilyand effectively producing pyrogen-free water has been findingenthusiastic recognition. Various attempts are being made in search of amethod capable of effectively removing pyrogens from water byadsorption. In the case of ion-exchange resin, synthetic adsorbent, andvarious species of activated carbon, for example, porous ion-exchangeresins (produced by Rohm and Haas Co. and marketed under registeredtrademark designations of "Amberlite" 200 and IRA-938) have beendemonstrated to produce some effect and synthetic adsorbents such as,for example, Amberlite XAD, and activated carbons have been reported aseffective, if not perfectly, in the Journal of Chemical Society ofJapan, No. 8, pp. 1547-1553 (1973).

SUMMARY OF THE INVENTION:

An object of this invention is to provide a carbonaceous adsorbent whichis capable of adsorbing various pyrogens dissolved in water to decreasethe concentration of pyrogens to the level of substantial absence.

Another object of this invention is to provide a method for the removalof endotoxin from water to the level of extremely low concentration.

Further object of this invention is to provide an improved method forthe removal of endotoxin which enables production of superpure water orultra-superpure water suitable for various applications.

This invention is directed to a carbonaceous adsorbent for the removalof pyrogens obtained by carbonizing porous beads of a cross-linkedpolymer.

This invention is also directed to a method for the removal of endotoxinin the production of pure water from deionized water resulting from thetreatment with ion-exchange resin, which method is characterized in thatthe removal of endotoxin from the deionized water is effected by thetreatment with a carbonaceous adsorbent obtained by carbonizing andoptionally further activating porous beads of a cross-linked polymer.

BRIEF DESCRIPTION OF THE DRAWING:

The single drawing is a graph showing the adsorption equilibria of acarbonaceous adsorbent according to the present invention and aconventional adsorbent.

DETAILED DESCRIPTION OF THE INVENTION:

As the polymer for the porous beads contemplated by this invention,generally a copolymer formed of a monovinyl monomer and a polyvinylmonomer is most desirable. This copolymer is produced in the form ofporous beads by subjecting the above monomers to a conventionalsuspension polymerization. The copolymer formed of styrene anddivinylbenzene is well-known. Naturally, even with the combination ofother monovinyl monomer and other polyvinyl monomer, this invention canbe accomplished.

For the beads of copolymer mentioned above to acquire porosity, it isnecessary that the monomers should be subjected to the suspensionpolymerization in the presence of a known additive suitable forimpartation of porosity. As typical additives for this purpose, therecan be cited solvents of a type soluble in monomers called"precipitants" and incapable of swelling the produced copolymer,solvents of a type soluble in monomers called "swelling agents" andcapable of swelling the produced copolymer, mixed solventssimultaneously containing the aforementioned swelling agents andprecipitants, organic liquids of a type formed of such swelling agentsand monovinyl linear polymers capable of forming a homogeneous liquidphase with the swelling agents, and insoluble macromolecules such aspolyalkylene glycols which are soluble in the monomer mixtures andinactive to the produced copolymer. The additives are not limited tothose cited above. Any of the other known agents capable of producingporous copolymers can be naturally adopted.

The porous cross-linked copolymer produced by the method describedabove, when necessary, may be sulfonated or chloromethylated and thenaminated into an ion-exchange resin. This ion-exchange resin is asdesirable for the purpose of this invention as the aforementioned porouscopolymer.

The porous beads of a cross-linked copolymer may be a commerciallyavailable product. For example, they may be ion-exchange resins of theaforementioned Amberlite series or various synthetic adsorbents.Besides, various commercially available products such as Diaion(registered trademark owned by Mitsubishi Chemical Industries Ltd.) andDowex (registered trademark owned by The Dow Chemical Company) arenaturally usable herein.

The desired adsorbent is formed by subjecting the porous beads ofcross-linked copolymer obtained as described above to a carbonizingtreatment by the conventional method. Examples of the conventionalmethod usable for the carbonization include those disclosed in thespecifications of Japanese Patent Laid-open Nos. 53,594/74, 50,088/78,126,390/76, 30,799/77 and 63,691/76. The desired carbonaceous adsorbentis obtained by infusibilizing porous beads of a cross-linked polymer aswith sulfuric acid, nitrogen dioxide, or chlorine and thermallydecomposing the infusibilized porous beads at a temperature in the rangeof 300° C. to 900° C. The adsorbent obtained as described above may beused in its unmodified form. It may be put to use, when necessary, afterit has been thoroughly activated as with steam or an aqueous zincchloride solution.

As a commercial product obtained by the method described above,Ambersorb (registered trademark owned by Rohm and Haas Co.) is availablein the market. It can be used in working the present invention. Thisadsorbent is in the form of beads, has a low ash content, and ischaracterized by excelling in wear resistance and physical strength.Besides radical differences in physical properties, the salientdifference between the adsorbent and commercially available powdered orgranulated activated carbon resides in the fact that the porous beads ofthe cross-linked polymer retain the skeletal structure thereof intactthrough the treatments of carbonization and activation. This salientdifference is believed to contribute to the wide difference in thecapacity for adsorption of pyrogens.

The adsorbent of this invention is used in the treatment of water formedical applications such as, for example, water for use in artificialinternal organs, water for injection, water for surgical operations,water for the preparation of solutions supplied in ampoules, water forthe preparation of Ringer's solution, and water for the preparation ofphysiological saline water, water for pharmaceutical products, and waterfor the production of semiconductor elements. For example, it is used inthe system for production of superpure water by treating normally purewater to the ultimate purity, i.e. the level of substantial absence ofpyrogens.

The absorbent, for example, Amberlite XE series produced by Rohm andHaas Co., is in the form of beads, has a low ash content, and ischaracterized by excelling in wear resistance and physical strength.These secondary characteristics have special significances in thetreatment of endotoxin in pure water.

Owing to these characteristics in addition to the capacity for effectiveadsorption of endotoxin, the use of the adsorbent permits the desiredremoval of endotoxin in pure water without impairing the quality of thewater under treatment.

The conventional activated carbon for the treatment of water had thedisadvantage that it constitutes a warm nursery for the growth ofbacteria because of its amorphousness, succumbs to disintegrationbecause of its deficiency in physical strength and wear resistance,persists in the form of finely divided particles within the system oftreatment, and consequently impairs the quality of the water undertreatment. Besides radical differences in physical properties, thesalient difference between the adsorbent and commercially availablepowdered or granulated activated carbon resides in the fact that theporous beads of the cross-linked polymer retain the skeletal structurethereof intact through the treatments of carbonization and activation.This salient difference is believed to contribute to the wide differencein the capacity for adsorption of endotoxin.

The desired treatment of the deionized water with the presentcarbonaceous adsorbent can be accomplished by a method which comprisespassing the deionized water through a column of a proper size packedwith the adsorbent.

The incorporation of the method of this invention in the simplifiedsystem for the production of pure water is accomplished by treating withthe aforementioned carbonaceous adsorbent the deionized water resultingfrom the treatment with an ion-exchange resin or the deionized waterresulting from the treatment with activated carbon plus the treatmentwith an ion-exchange resin.

The superpure water for medical use such as the water used for thepreparation of solutions for injection containing no pyrogenic substanceand the ultra-superpure water necessary for the production ofsemiconductor elements of increasingly high integration are required tofulfil the exacting standard that the number of live microorganisms, thesource of pyrogen, should not exceed 0.02/ml. In the production of suchsuperpure water or ultra-superpure water, live microorganisms are killedby the ultraviolet light. Since the endotoxin is released from thekilled microorganisms into the water, the treatment for the removal ofendotoxin contemplated by the present invention is desired to be carriedout after the treatment with the ultraviolet light and before thetreatment with a regeneration type mixed-bed ion-exchange resin columnor to be carried out before the treatment with a filtration membrane atthe final step of the entire process.

To be more specific, in the production of superpure water orultra-superpure water, the removal of endotoxin contemplated by thepresent invention can be effectively performed at a desired pointbetween a water storage tank and a filtration membrane in a whole seriesof treatments using an ion-exchange resin column, the water storagetank, an ultraviolet light sterilizer, a regeneration type mixed-bedion-exchange resin column, and a filtration membrane such as anultrafiltration membrane or a reverse-osmosis membrane.

Compared with the conventional activated carbon adsorbent, thecarbonaceous adsorbent of this invention can be used very simply andeffectively for the production of water containing substantially nopyrogens. Moreover, the present carbonaceous adsorbent enables easily toproduce pure (superpure or ultra-superpure) water containingsubstantially no endotoxin in a large amount.

The present invention will be described specifically below withreference to working examples.

EXAMPLE 1:

In 1.5 liters of distilled water, 5.0 g of polyvinyl alcohol, 2 gcarboxymethyl cellulose, and 56 g of NaCl were dissolved. To theresultant solution, a mixture consisting of 200 g of styrene, 132 g ofdivinylbenzene (commercial product 59%), 240 g of butanol, and 1.5 g ofbenzoyl peroxide was added and reacted under stirring at 85° C. for sixhours. In 500 g of 15% fuming sulfuric acid, 40 g of the porous beads ofthe cross-linked polymer obtained were sulfonated at 110° C. for sixhours. Then they were washed first with H₂ SO₄ and then with water anddried. Subsequently, in N₂, the sulfonated porous beads of the polymerwere calcined at a temperature increasing rate of 300° C./hr up to 950°C. The resultant calcined porous beads had an apparent specific gravityof 0.5 and a pore volume of 0.6 g/cc. The porous beads of carbon wereactivated in an atmosphere of steam at 800° C. for two hours.Consequently, there was obtained a carbonaceous adsorbent having asurface area of 1,100 m² /g.

EXAMPLE 2:

In 1.5 liters of distilled water, 5 g of polyvinyl alcohol, 2.5 g ofcarboxymethyl cellulose, and 56 g of NaCl were dissolved. To theresultant solution, a mixture consisting of 200 g of styrene, 132 g ofdivinylbenzene (commercial product, 59%), 240 g of toluene, and 1.5 g ofbenzoyl peroxide was added and reacted under stirring at 85° C. for sixhours. In 500 g of 15% fuming sulfuric acid, 40 g of the porous beads ofpolymer consequently obtained was sulfonated at 110° C. for six hours,washed first with sulfuric acid and then with water, and dried. Then, inan atmosphere of N₂, the porous beads of polymer were calcined at atemperature increasing rate of 300° C./hr up to 950° C. They had anapparent specific gravity of 0.55 and a pore volume of 0.6 cc/g. Theporous beads of carbon were activated in an atmosphere of steam at 800°C. for two hours. Consequently, there was obtained a carbonaceousadsorbent having a surface area of 1,020 m² /g.

EXAMPLE 3:

The pyrogens contained in the town water stored in a feed tank installedon the roof of a five-storey building were tested for equilibriumconcentration with respect to a carbonaceous adsorbents, AmbersorbXE-340, 347, and 348 and activated carbon beads (oil pitch) produced byKureha Chemical Industry Co., Ltd. For comparison, the same pyrogenswere tested for equilibrium concentration with respect to uncarbonizedporous beads of cross-linked polymer adsorbent, XAD-2. The results wereas shown in the accompanying drawing. It is noted from the data that theaforementioned carbonaceous adsorbent showed a large capacity foradsorption in a liquid containing various salts and organic carbons ofhigh concentrations as compared with the activated carbon. The pyrogenconcentration was determined with a toxinometer made by Wako Junyaku K.K., using limulus amerbocyte lysate also made by the same company. Theanalyses of the adsorbents used and those of the water used were shownbelow.

    ______________________________________                                                               Kureha                                                 Ambersorb              BAC                                                    XE-340       -347     -348     MP     XAD-2                                   ______________________________________                                        Surface 374      345      500    1160   300                                   area                                                                          (m.sup.2 /g)                                                                  Pore    0.346    0.425    0.580  0.633  0.64                                  volume                                                                        (m.sup.3 /g)                                                                  Bulk    0.6      0.7      0.6    0.6    --                                    density                                                                       (g/cm.sup.3)                                                                  Particle                                                                              0.84˜                                                                            0.84˜                                                                            0.84˜                                                                          0.59˜                                                                          0.25˜                           diameter                                                                              0.30     0.30     0.30   0.25   0.85                                  (mm)                                                                          Ash     0.2      0.16     0.02   0.01   --                                    content                                                                       (%)                                                                           ______________________________________                                    

    ______________________________________                                        Analyses of town water                                                        ______________________________________                                        Total organic                                                                           1.5 mg/l   Calcium      16 mg/l                                     carbon                                                                        Electro-  260 MS/cm  Sodium       24 mg/l                                     conductivity                                                                  Free chlorine                                                                           0.2 mg/l                                                            Chlorine ion                                                                            41 mg/l    Number of live                                                                             0/100 ml                                                         microorganims                                            Sulfate ion                                                                             33 mg/l                                                             Silica    14 mg/l                                                             ______________________________________                                    

EXAMPLE 4:

A town water containing pyrogens in a concentration of 80 ng/ml was usedas raw water. It was distilled once in a distillation kettle made ofcopper. Then, it was distilled in a distillation kettle made of Pyrexglass to produce distilled water having an electroconductivity of 1.2 MΩ/cm. The distilled water emanating from the distillation kettle wasreceived in a polyethylene container having an inner volume of 20 litersand provided with a carbon dioxide absorption tube and left standing fortwo days (during which period, about 2 liters of the water was taken viaa faucet disposed in the lower part of the container). During thisstanding, the distilled water was microorganically contaminated (150live microorganisms/100 ml). In the water, the presence of pyrogens at aconcentration of 1 ng/ml was detected. When this water was passedthrough glass columns measuring 10 cm in inside diameter and 30 cm inheight and severally containing 10 g each of Ambersorb XE-347, thecarbonaceous adsorbent of Example 1 obtained by carbonizing andactivating the macroporous synthetic polymer indicated below, and acommercially available Pittsburgh granular activated carbon at a spacevelocity (SV) of 4 (a liquid speed twice the amount of adsorbent perhour). The amounts of water treated until the pyrogen detection limit,0.01 ng/ml, were shown below.

    ______________________________________                                                                      Pittsburg                                                           Adsorbent granular                                                  Ambersorb of        activated                                                 XE-347    Example 1 carbon                                          ______________________________________                                        Amount treated                                                                            20          18        4.2                                         (lit) 25° C.                                                           Amount treated                                                                            17          15        3.0                                         (lit) 40° C.                                                           ______________________________________                                    

EXAMPLE 5:

When 50 liters of physiological saline water containing 0.9 g of sodiumchloride per 100 cc of the sterilized water conforming with the standardof Japanese Pharmacopoeia were prepared, it was found to have beencontaminated with pyrogens to a level of 0.15 ng/ml. Two halves of thissaline water were passed through glass columns 3 cm in inside diameterseverally packed with 250 ml of Pittsburg coconut sheel activated carbonand 250 ml of Ambersorb XE-348 at a space velocity (SV) of 20. In thephysiological saline water passed through the Ambersorb XE-348, thepyrogen concentration was found to be below 0.01 ng/ml. In thephysiological saline water treated with the activated carbon, thepyrogen concentration was 0.03 ng/ml.

EXAMPLE 6:

To recover various proteins and nucleic acids from colon bacillus (E.Coli: IAM 1268) cell extract, the cell extract was each 2.5 ml (PH 5.6)in volume two glass columns 3 cm in diameter packed severally with 100ml of Ambersorb XE-340 and 100 ml of Tsurumi Soda (Ltd.) granularactivated carbon HC-30. Then, the water for injection produced by OtsukaPharmaceutical was passed through the glass columns at a space velocity(SV) of 1 at room temperature to effect removal of endotoxin.Consequently, there were obtained eluates each 200 ml in volume. Theendotoxin concentrations in these eluates were as follows:

    ______________________________________                                                     Endotoxin concentration                                          ______________________________________                                        Raw liquid     4 × 10.sup.5                                                            (ng/2.5 ml of cell extract)                                    Eluate from    <0.01 (mg/ml)                                                  Ambersorb XE-340                                                              Eluate from Tsurumi                                                                          0.5 (mg/ml)                                                    Soda granular                                                                 activated carbon                                                              ______________________________________                                    

EXAMPLE 7:

A system intended for the production of deionized water from town wateras the raw material and composed of a column of granular activatedcarbon, a column of gel type cation-exchange resin, a column of gel typeanion-exchange resin, and a column of mixed-bed type ion-exchange resinin the form of porous beads of cross-linked polymer was intermittentlyoperated by feeding about 100 liters of the town water over a durationof about four hours per cycle. After this operation was continued forabout two weeks, the endotoxin began to leak in the deionized water atan average level of 1.5 ng/ml.

Then, the gel type cation- and anion-exchange resins were regenerated bythe conventional method. After this regeneration, the passage of thetown water through the system was started again. In this operation, theendotoxin began to leak in the deionized water at a higher level thanbefore on the second day of the operation.

When the entire system was searched in an effort to find the cause forthe leak, the bed of granular activated carbon in the column was foundto be acting as a warm pursery for the growth of bacteria. So, the pipefor supply of the town water was replaced with three pipes adapted topass an equal amount of water. The first pipe was fitted with a columnpacked with 300 g of Ambersorb XE-347, the second pipe a column packedwith 300 g of Pittsburg granular activated carbon produced by CalgonCorp., and the third pipe a column packed with 300 g of Amberlite XAD-2,i.e. uncarbonized porous beads of cross-linked polymer respectivelybefore the supply of the town water was started.

The amounts of the town water treated before the endotoxin detectionlimit, 0.01 ng/ml, were shown below.

    ______________________________________                                                Ambersorb Pittsburg granular                                                  XE-347    activated carbon                                                                           XAD-2                                          ______________________________________                                        Amount treated                                                                          1200        540          600                                        (lit)                                                                         ______________________________________                                    

EXAMPLE 8:

In a small laboratory-grade system intended for the production of purewater from town water as the raw material and adapted to pass the townwater through a column of granular activated carbon, a column of geltype cation-exchange resin, a column of anion-exchange resin, and acolumn of mixed-bed type ion-exchange resin in the form of porous beadsof cross-linked polymer, store 200 liters of the treated town water in afeed tank (the section of the deionized water production system on theraw water side was automatically actuated so as to allow the feed tankto keep 200 liters of the water at all times), forward the water fromthe feed tank through an ultraviolet light sterilizer, a regenerationtype mixed-bed ion-exchange resin column, and an ultrafiltrationmembrane to the point of actual use (faucet), and return the unusedwater to the feed tank, collection of the treated water was continued(about 100 liters of water of a purity of 18.2 MΩ.cm per day). After oneweek of this operation, the water was taken as a sample from a samplingpoint located between the regeneration type mixed-bed ion-exchange resincolumn and the ultrafiltration membrane and analyzed. The sample wasfound to contain endotoxin in a concentration of 0.5 ng/ml.

So, a column packed with 500 g of Ambersorb XE-340 was inserted in thesystem behind the ultraviolet light sterilizer, the endotoxin levelwithin the system was below the detection limit (0.01 ng/ml) even afternine days' passage of the town water. When the same amount of beads ofactivated carbon, BAC-MP, produced by Kureha Chemical Industry Co., Ltd.were used in the place of Ambersorb XE-340, leakage of endotoxin beganto occur on the fourth day of the passage of the town water.

EXAMPLE 9:

A system intended for the production of deionized water from town wateras the raw material and composed of a column of granular activatedcarbon, a column of gel type cation exchange resin, a column of gel typeof anion-exchange resin, and a column of mixed-bed type ion-exchangeresin in the form of porous beads of crosslinked copolymer wasintermittently operated by feeding about 100 liters of the town waterover a duration of about two hours, the endotoxin began to leak in thedeionized water at an average level of 1.5 ng/ml.

Then, the pipe for supply of the town water was replaced with threepipes adopted to pass an equal amount of water. The first pipe wasfitted with a column packed with 100 g of Ambersorb XE-347, the secondpipe a column packed with a mixture of 50 g of a carbonaceous adsorbentmade by carbonizing a synthetic adsorbent and 50 g of a carbonaceousadsorbent made by carbonizing and activating a synthetic adsorbent andthe third pipe a column packed with 100 g of an uncarbonized poroussynthetic polymer for comparison, respectively before the supply of thetown water was started.

The amounts of the town water treated before the endotoxin detectionlimit, 0.01 ng/ml, was shown as below.

    ______________________________________                                        (1)   Ambersorb XE-347         1250 l                                         (2)   Carbonaceous Adsorbent   1180 l                                               (carbonized adsorbent + carbonized                                            and activated adsorbent)                                                (3)   Porous synthetic polymer  580 l                                         ______________________________________                                    

The preparation method of the carbonaceous adsorbent is shown below.

The porous synthetic polymer (3) was obtained by dissolving 5.0 g ofpolyvinylalcohol, 2 g of carboxymethyl cellulose and 56 g of NaCl in 1.5l of distilled water, adding a mixture of 200 g of styrene, 132 g ofdivinylbenzene (purity: 59%), 240 g of butanol, and 1.5 g of benzoylperoxide, and reacting the resultant mixture for 6 hours at 85° C. understirring.

Then, 250 g of the porous crosslinked polymer was sulfonated in 3100 gof fuming sulfuric acid for 6 hours at 110° C. The polymer was washedwith water after washed with sulfuric acid, and then was dried. Thecarbonaceous adsorbent (2), 0.5 g/cc of density, and 0.6 g/cc of porevolume, was obtained by carbonizing the sulfonated polymer until 950° C.at 300° C./hour in a rise in temperature in N₂ gas. A part of thecarbonaceous adsorbent produced was activated with steam for 2 hours at800° C. The adsorbent activated had 1100 m² /g of the surface area.

What is claimed is:
 1. A method for the removal of pyrogenic matterdissolved in water, comprising:contacting the water containing pyrogenicmatter with a carbonaceous adsorbent prepared by carbonizing porousbeads of a cross-linked polymer, wherein the cross-linked porous beadsretain their skeletal structure intact through the carbonizationtreatment.
 2. A method for the removal of endotoxins from water whichhas been deionized by treatment with an ion exchange resin, whichcomprises:contacting the deionized water containing endotoxins with acarbonaceous adsorbent prepared by carbonizing porous beads of across-linked polymer, wherein the carbonizing treatment allows theskeletal structure of the cross-linked polymer to remain intact.
 3. Themethod as claimed in claim 2 wherein the adsorbent is activated withsteam or an aqueous zinc chloride solution.
 4. The method as claimed inclaim 2 wherein the adsorbent is obtained by carbonizing porous beads ofa cross-linked copolymer of styrene and divinylbenzene or by carbonizingthese porous beads and then activating the resulting carbonizationproduct.
 5. The method as claimed in claim 2, wherein the porous beadsare infusibilized before they are carbonized.
 6. In a process forproducing super pure water or ultra-super pure water by passing watercontaining a pyrogenic substance through a series of steps ofion-exchange, water storage, sterilization with ultraviolet light, ionexchange with a regeneration type mixed-bed ion exchange resin,filtration with an ultrafiltration membrane or a reverse-osmosismembrane, the improvement comprising:after storage of the water, butprior to filtration, contacting the water containing a pyrogenicsubstance with a carbonaceous adsorbent prepared by carbonizing porousbeads of a cross-linked polymer, wherein the carbonizing treatmentallows the skeletal structure of the cross-linked polymer to remainintact.